Internal-combustion engine



March 27, 1934. K MQHR I INTERNAL COMBUSTION ENGINE Filed Aug 1, 1950Patented Mari 27, 1934 v 1,952,275 INTERNAL-COMBUSTION ENGINE Karl Mohr,Kiel, Germany, aleignor to Fried.

Krupp Germaniawerl't Garden, Germany Aktlengeeellechalt, Kiel-Application August 1, 1930, Serial No. 472,437

In Germany December 2, 1929 3 Claims.

The invention relates to two stroke internal combustion engines equippedwith means for transverse scavenging.

In the transverse scavenging arrangements in 5 which the inlet andexhaust ports are situated opposite one another on the periphery of thecylinder it is very difilcult to raise the scavenging current up to thecylinder cover on the entrance side. Even if one succeeds in raising theentering scavenging current initially for a certain distance bymechanical means such as diverting surfaces on the piston or verysteeply upwardly directed inlet ports, the current nevertheless verysoon deviates short-circuitedly to- 16 ward the exhaust ports, becausewhirls are formed between the cylinder wall and the rising current whichwhirls urge the current away from the cylinder wall. As a consequencethereof a whirl of waste gases is produced in the 20 upper portion ofthe cylinder which whirl persists during the scavenging period andprevents scavenging of this cylinder portion.

Now it has been tried for instance, to give the current an upwarddirection by upwardly inclined supporting currents directed toward theinlet side; such a collision of currents, however, results in theformation of violent whirls, as experience has shown, which preventcorrect guiding of the scaven ing current. This proposal therefore doesnot solve the problem satisfactorily.

According .to the invention the object aimed at of raising the enteringscavenging current on the entrance side of the cylinder up to thecylinder cover is obtained in simple manner by the entering scavengingcurrent being directed upwardly toward that cylinder end which is remotefrom the inlet and exhaust ports, and by reducing or entirelyeliminating the corner remaining between the scavenging current andcylinder wall on the entrance side by providing auxiliary exhaust portsabove the inlet ports, these auxiliary ports sucking the scavengingcurrent up to the cylinder wall.

It may be noted that in a known transverse scavenging arrangementadditional exhaust ports are provided above nearly horizontally directedinlet ports, in order to increase the useful exhaust area. This portarrangement, however, is 5 not capable of sucking the scavenging currentup to the cylinder wall as the current already from the begirming iscarried away too far from the additional exhaust ports and cannot bedeflected by nearly a right'angle.

In order that the invention can be more readi- 1y understood, anembodiment of the same is illustrated by way of example in theaccompanying drawing in which Figure 1 shows the course of thescavenging current in the cylinder when fitted with the usual upwardlydirected inlet ports, without application of the invention, and

Figure 2 shows the course or the scaven ing current in a cylinderdesigned according to the invention.

In Figure 1 the upwardly inclined inlet scavenging ports are denoted byA, while B denotes the oppositely situated exhaust ports; C is thepiston. The scavenging air streams here through the cylinder in thedirection of the arrows and in so doing produces at the cylinder wall Dthe edge whirls E and at the cylinder cover F the known upper permanentwaste gas whirl G. The cylinder is thus scavenged only in part.

Now according to the invention, in Figure 2, v

auxiliary exhaust or relief ports H are provided in the cylinder wall Dabove the upwardly directed inlet ports. During the backward stroke ofthe piston C a small quantity of waste gases escapes through these portsH, as indicated by the horizontal arrow, whereby pressure belowatmospheric is produced at the entrance side of the cylinder wall whichpressure causes the entering scavenging current to be sucked up to thecylinder wall. Edge whirls as occurring in the cylinder according toFigure 1 cannot thus be formed at all on this place, but the scavengingcurrent under the action of the auxiliary exhaust ports is sucked up tothe cylinder wall and even in long stroke engines rises up withouthindrance to the cylinder cover. This results in a more thoroughscavenging being obtained than it was hitherto possible by transversescavenging arrangements.

The auxiliary exhaust ports H communicate with the exhaust duct of theengine. They can have only a small sectional area and extend beyond themain outlet ports B but little or not at all. A notable loss ofscavenging air thus does not take place. Besides, as with theabovementioned known additional ports, an increase of the time crosssection for the pre-exhaust is obtained.

As to be seen from the foregoing, the satisfactory scavenging eilect isbased on the cooperation of the upwardly directed scavenging currentwith the sucking eflect of the auxiliary exhaust ports situated abovethe inlet ports.

I claim:-'

1. In a cylinder for two stroke cycle internal combustion engines ascavenging arrangement comprising scavenging air inlet ports having aninclined upward direction, exhaust ports diametrally opposite said inletports, and relief ports situated closely above said inlet ports and openduring the entire period that the scavenging air inlet ports areuncovered adapted to suck the scavenging currents adjacent to the wallof said cylinder.

2. In a cylinder for two stroke cycle internal combustion engines ascavenging arrangement comprising scavenging air inlet ports having aninclined upward direction, exhaust ports diametrally opposite said inletports, and auxiliary exhaust ports situated closely above said inletports and approximately within the same height as said exhaust ports,operating as such durin the scavenging operation.

3. Ina cylinder for two stroke cycle internal combustion engines, ascavenging arrangement comprising at least one scavenging air inlet porthaving an inclined direction toward the head end of said cylinder, atleast one exhaust port diametrally opposite said inlet port, and atleast one relief port situated closely beyond said inlet port and openduring the entire period that the scavenging air inlet port isuncovered, adapted to suck the scavenging currents adjacent to the wallof said cylinder.

V KARL MOI-IR.

